In the field of communications, in order to improve the capacity and coverage of hotspots, apart from intensive deployment of macro cells, another approach which may be considered is to enhance the local throughput performance through intensive deployment of micro-cells. However, in this heterogeneous network scenario, there may be many problems. For example, on one hand, different transmission power of different base stations may cause power imbalance; especially in the case of co-frequency deployment, it may bring great interference to a user at an edge of a cell; and interference caused by the heterogeneous network deployment affects handover performance, especially in the case of co-frequency deployment. On the other hand, the increasing number of network nodes may increase the number of handover times, resulting in an increase in network signaling load overheads; if the backhaul between different nodes is not ideal, then one terminal cannot be served by a plurality of nodes, and thus the highest data peak rate and the optimal resource utilization cannot be achieved. Therefore, a dual-connectivity solution can be used to solve the problems existed in these heterogeneous networks. The so-called dual connectivity means that a terminal is connected to two cells at the same time, where a macro cell is used to fulfill the functions of the control plane, including connection management and mobility management.
Dual connectivity technology refers to an enhancement technology where User Equipment (UE) uses radio resources from two nodes which are connected with each other by a non-ideal link. For a UE of dual connectivity, each evolved Node B (eNB) may play a different role. These roles do not need to be associated with power levels of the eNBs and each eNB may play different roles for different UE. As shown in FIG. 1, the UE completes user plane data transmission by aggregating radio resources of the two eNBs, while control plane data is still maintained at the macro eNB.
However, since existing mechanism only supports offloading between a master eNB (MeNB) and a secondary eNB (SeNB), when a Third Generation Partnership Project (3GPP) access network is congested, a Wireless Local Area Network (WLAN) access network may be idle. In addition, the protocol stack used when an eNB transmits user data is shown in FIG. 2; the protocol stack used when a WLAN access network transmits user data is shown in FIG. 3, and through comparison, it can be seen that the wireless access technology used by the eNB is different from that used by the WLAN access network and their protocol stacks are also different, so the offloading technology used between eNBs cannot be directly used between an eNB and a WLAN access network.
It thus can be seen that the existing mechanism does not apply to offloading between an eNB and a WLAN network. Therefore, when the 3GPP access network is congested, the eNB cannot utilize the capacity of the WLAN to offload a part of traffic from the 3GPP access network to the WLAN network.